Geomorphology and dating of the sand ramp (Kouh Rig) in Farashah, Taft, on the purpose of determining the last quaternary features of the northern slopes of Shirkouh

The sand ramp (or Kouh Rig as in Farsi) is a phenomenon formed by accumulation of sand and other materials in the upwind side or leeside of a mountain slope. This formation is due to the multiple interactions of extreme wind actions, feeding and displacement of sand, physical obstacles, and slope-induced processes. Unfortunately, the phenomenon is not well-known in the physical geography studies of Iran. The sand ramp, about five km west of Taft city, was selected to be investigated due to its relative intactness. Some sand samples were extracted from the depth of 0.4m and 4.2m on the top of the sand ramp. The samples were cleaned several times to provide pure quartz particles that were then analysed using the Optically Stimulated Luminescence (OSL) dating method. The results of dating indicated that the top half section of Farashâh sand ramp was probably accumulated during or near the last glacial maximum phase (something between 18000 to 24000 years ago). The results also emphasize that, in contrast to the theory of cold and wet conditions, with more rain during the glacial phases of Quaternary on the Iranian plateau, at least for parts of the glacial (cold) phases, colder and drier environments with very active winds were dominant on the central Iran.